Small fixes to Geo database configuration doc

doc/gitlab-geo/database.md

@@ -313,13 +313,10 @@ because we have not yet configured the secondary server. This is the next step.
     addresses with addresses appropriate to your network configuration:
 
     ```ruby
-    geo_primary_role['enable'] = true
-    
     # Secondary addresses
-    # - replace '5.6.7.8' with the secondary public address
+    # - replace '5.6.7.8' with the secondary private address
     postgresql['listen_address'] = '5.6.7.8'
     postgresql['trust_auth_cidr_addresses'] = ['127.0.0.1/32','5.6.7.8/32']
-    postgresql['md5_auth_cidr_addresses'] = ['5.6.7.8/32']
 
     # gitlab database user's password (defined previously)
     gitlab_rails['db_password'] = 'mypassword'
@@ -477,4 +474,5 @@ Read the [troubleshooting document](troubleshooting.md).
 [pgback]: http://www.postgresql.org/docs/9.2/static/app-pgbasebackup.html
 [external postgresql]: #external-postgresql-instances
 [tracking]: database_source.md#enable-tracking-database-on-the-secondary-server
+[FDW]: https://www.postgresql.org/docs/9.6/static/postgres-fdw.html
 [toc]: README.md#using-omnibus-gitlab